The present invention relates to a power source connection device of a showcase which supplies power to a fluorescent lamp and the like.
In general, a showcase or the like is provided with a power source connection device including a power source socket connected to the inside of a chamber of a main body of the showcase and a power source plug which is inserted into this power source socket to supply power to a fluorescent lamp and the like. In a conventional power source connection device described in, for example, Japanese Patent Application Laid-Open No. 11-273775, the power source socket is provided with a peripheral wall at an outer periphery thereof, and a recessed portion in which an electrode portion is formed at an inner portion of the peripheral wall. This electrode portion is provided with an insertion port for the power source. On the other hand, the power source plug includes a movable portion which is connected to a wiring line extending to the fluorescent lamp and the like, and a cylindrical portion. A terminal is disposed at a bottom portion of the cylindrical portion. Therefore, to insert the power source plug into the electrode portion of the power source socket, the terminal of the power source-plug is inserted into the insertion port for the power source of the power source socket.
On the other hand, the power source plug connected to the power source connection device is a power source plug of the fluorescent lamp or the like arranged under a front end of each of a plurality of stages of shelves of a shelf device arranged in the chamber. To change an in-chamber layout or the like, an arrangement position of the shelf device is changed. In consequence, the power source socket to which the power source plug is to be connected is changed. Therefore, a plurality of power source sockets are arranged in a vertical direction at a partition plate constituting a back wall of the chamber. However, the power source socket to which the power source plug is connected and the power source socket to which the power source plug is not connected are arranged, depending on a position of the shelf device.
Therefore, the power source socket which is not connected to the power source plug has a problem that, when an in-chamber temperature drops to generate dew condensation water, this dew condensation water enters the electrode portion formed at the power source socket to cause power leakage. To solve the problem, the power source socket constituting the power source connection device described above is rotatably provided with a cap which covers the electrode portion.
However, in the above-mentioned power source connection device, even in a state in which the power source plug is connected to the power source socket, the temperature of the power source socket drops to generate the dew condensation water, because the power source socket is arranged on the partition plate which separates the inside of the chamber and a cold air passage from each other. This dew condensation water turns to frost attached between the power source socket and the power source plug. There is also a problem that, when ice gradually grows, the power source plug drops down from the power source socket. Once the dew condensation water enters between the power source socket and the power source plug to generate the frost, it is difficult to securely attach the power source plug to the power source socket until the frost is removed.
Even in a conventional power source connection device, a protrusion extending in a peripheral direction is formed on an inner circumferential portion of the cylindrical portion of the power source plug, and the power source plug is inhibited from easily dropping down from the power source socket. However, in such a structure, when the power source plug is attached to the power source socket, it cannot be recognized that the terminal of the power source plug has securely been inserted into an appropriate position of the electrode portion of the power source socket. Therefore, the power source plug can be attached to the power source socket only halfway in many cases. In such a case, there has been a problem that the power source plug drops down from the power source socket owing to growth of the attached frost, and there has also been a problem that the power source plug easily drops down from the power source socket owing to a cause other than an influence of the attached frost.
Moreover, in the conventional power source connection device, the cap to cover the electrode portion of the power source socket to which the power source plug is not connected is arranged at the power source socket itself. However, in such a constitution, a constitution of the power source socket itself becomes complicated. Since cap structures are employed in all of the power source sockets, the number of the components increases, and a steep rise of cost might be incurred.